1. Field of the Invention
The present invention relates to a SAW filter adapted to a communication apparatus and the like, and to a method of manufacturing the same.
2. Description of the Related Art
Referring to figures illustrating a surface acoustic wave device for use in a conventional SAW filter and a method of manufacturing the same, FIG. 10 is a plan view illustrating a state where a conventional surface acoustic wave device is formed on a piezoelectric substrate, FIG. 11 is an explanatory diagram illustrating a first process according to a method of manufacturing the conventional surface acoustic wave device, and FIG. 12 is an explanatory diagram illustrating a second process according to the method of manufacturing the conventional surface acoustic wave device.
Next, configuration of the conventional surface acoustic wave device will be described with reference to FIG. 10. On one side of a piezoelectric substrate 51 are provided one surface acoustic wave device 52 constituted by a conductor and a pair of reflectors 53 disposed at both sides of the surface acoustic wave device 52 and constituted by a conductor.
In addition, the surface acoustic wave device 52 includes a pair of opposite interdigitated electrodes 52a and 52b and connecting electrodes 52c and 52d connected to the pair of interdigitated electrodes 52a and 52b. In addition, on the one side of a piezoelectric substrate 51 are provided a conductor removing part 54a at most of the places except for the surface acoustic wave device 52 and the reflector 53 and an inter-electrode removing part 54b with no conductor between the pair of interdigitated electrodes 52a and 52b (for example, see Japanese Unexamined Patent Application Publication No. 2002-374137).
In this manner, however, in the conventional SAW filter, since the conductor removing part 54a is provided at most of the places of the piezoelectric substrate 51 except for the surface acoustic wave device 52 and the reflector 53, it is a difficult process with low productivity and increased costs to provide the conductor removing part 54a. 
Next, a manufacturing method of the conventional SAW filter will be described with reference to FIGS. 10 to 12. First, the piezoelectric substrate 51 having a conductor pattern 54 formed on the entire of the one side of the piezoelectric substrate 51 is prepared, and then, as shown in FIG. 11, the pair of interdigitated electrodes 52a and 52b made when the inter-electrode removing portion 54b is provided and the pair of reflectors 53 are formed by a photolithography process.
At this time, since the pair of interdigitated electrodes 52a and 52b and the pair of reflectors 53 are connected to the conductor pattern 54 to prevent pyroelectric breakdown and thus have the same potential as the conductor pattern 54, no pyroelectric breakdown occurs when the photolithography process is performed.
Next, as shown in FIG. 12, the connecting electrodes 52c and 52d connected to the pair of interdigitated electrodes 52a and 52b are formed on the conductor pattern 54. However, similarly, since the pair of interdigitated electrodes 52a and 52b have the same potential as the conductor pattern 54, no pyroelectric breakdown occurs when the photolithography process is performed.
Thereafter, as shown in FIG. 10, the SAW filter is completed by forming the conductor removing part 54a by a photolithography process in the conductor pattern 54 at a place except for the surface acoustic wave device 52 and the reflectors 53 (for example, see Japanese Unexamined Patent Application Publication No. 2002-374137).
However, in the conventional method of manufacturing the conventional SAW filter, since the conductor removing part 54a for removing the conductor pattern 54 is provided at most of the places of the piezoelectric substrate 51 except for the surface acoustic wave device 52 and the reflectors 53, it is a difficult process with low productivity and increased costs to provide the conductor removing part 54a. 
As described above, in the conventional SAW filter and the method of manufacturing the same, since the conductor removing part 54a for removing the conductor pattern 54 is provided at most of the places of the piezoelectric substrate 51 except for the surface acoustic wave device 52 and the reflectors 53, it is a difficult process with low productivity and increased costs to provide the conductor removing part 54a. 